Paper machine and reconditioning method of paper conveying belt

ABSTRACT

[Problem to be solved] To provide a paper machine that can recover function of a belt being deteriorated in wet paper peeling performance while running the conveying belt without stopping the paper machine operation, and also can suitably modify or recondition the belt surface roughness according to operative condition of the paper machine, and to provide a method to recondition the paper conveying belt using such a paper machine.  
     [Solving Means] Providing a press device having a pair of paper conveying endless belt and a polishing device disposed on a return side of the paper conveying belt having a polisher to polish a wet paper contacting face of the paper conveying belt, which are arranged in such a way that the polisher polishes the wet paper contacting face of the paper conveying belt to enhance wet paper peeling performance that has been deteriorated by means of controlling the surface smoothness, or to enable to modify or recondition suitably the surface roughness of the belt according to the operative condition of the paper machine.

TECHNICAL FIELD

The present invention relates to a paper machine and a reconditioning method for a paper conveying belt. More particularly, the present invention relates to a paper machine provided with a polishing device to recover deteriorated wet paper peeling performance of paper conveying belt while the paper machine is running, or to modify or recondition suitably roughness of the belt surface according to operational condition of the paper machine, and also relates to a method of reconditioning the paper conveying belt using the same polishing device.

BACKGROUND

A paper machine includes generally a wire part, a press part and a dryer part. A wire part, a press part and a dryer part are arranged along the conveying direction of a wet paper in the above mentioned order. The wet paper is conveyed through handing over by paper conveying tools disposed in respective parts of the wire part, the press part and the dryer part, while in the press part water is squeezed (water suction) and finally, the paper is dried on a dryer canvas, which is a paper conveying device in the dryer part. A press device disposed in the press part includes a plurality of pressing mechanisms arranged in series along the conveying direction of the wet paper.

There are two types in a press mechanism, i.e. a roll press type, which pressurizes paper conveying belts having wet paper being sandwiched by two rolls in a manner of pinching the belt, and a shoe-press type, which presses the same by a roll and a shoe. Both types of press mechanism make the paper conveying belt, which is made of felt with water absorbing property, absorb water while squeezing water from the wet paper by pressurizing the wet paper being conveyed by the conveying belt substantially with the same speed and in the same direction by means of two rolls or a roll and a shoe together with the paper conveying belt.

Particularly, the shoe-press type paper machine, compared with a more ordinary roll-press type paper machine, can take larger pressing zone in pressurizing portion (nip) of a press, accordingly giving longer pressing time, which results in a better water absorbing property.

A paper conveying belt requires a different function for each press part in operation respectively. For example, in a press device having a first press mechanism and a second press mechanism, a belt (felt) with a better water absorbing property is used for top side and bottom side of the first press mechanism in order to absorb water squeezed from the wet paper. The paper conveying belt of the second press mechanism disposed in the down stream side in the conveying direction of the wet paper in a press part requires a smooth contacting surface with the wet paper, particularly for the purpose of smoothening the wet paper surface.

On the other hand, between the wire part and the press part, between two press mechanisms of the press device, such as between the first press area and the second press area, and between the press part and the dryer part, it is necessary to hand over the wet paper to a paper conveying tool (e.g. a dryer canvas) of the subsequent process. Consequently a paper conveying belt of press device particularly requires, not only wet paper water squeezing function and wet paper conveying function but also paper separating function (wet paper peeling performance) so that wet paper can be removed smoothly from paper conveying belt when handing over the wet paper to the subsequent process.

Wet paper peeling performance is herein explained. Conveying belt having extremely smooth surface, in general, generates a uniform thickness water film between the wet paper and the belt, which provides strong sticking performance between the wet paper and the belt each other, and hence the paper peeling function is inclined to get worse. Especially the conveying belt disposed in the down stream side of the conveying direction in the press part requires, as described above, a smoothening function. Smoothening of belt for obtaining smooth surface in wet paper and improvement of paper peeling performance are contradictory subjects and it is difficult to solve the both all at once.

As a paper conveying belt that has been improved in wet paper peeling performance for handing over the wet paper, such a belt is known that has hydrophobic material arranged in a part of wet paper mounting face (wet paper contacting face) conveying wet paper thereon (Patent Document 1). More particularly, this paper conveying belt is composed of a polymer elastic member having a wet paper mounting face thereon and a facial layer forming body disposed within the polymer elastic member, and either of the two is arranged to be a hydrophobic material. Accordingly the water rejecting part and the water condensing part are deployed in dispersing manner so that wet paper peeling performance is enhanced through breakage of water film between the wet paper mounting face and the wet paper.

In addition, such a conveying belt is also known that has a structure in which fiber body is protruded from the wet paper side surface of the paper conveying belt (Patent Document 2). In this conveying belt, water is grasped in the fiber bodies protruded from the wet paper side surface via capillary phenomenon. Although the wet paper is stuck to the belt, the water film does not become so strong for sticking and hence handing over to the subsequent process is carried out smoothly.

[Patent Document 1] Publication of Unexamined Patent Application No. 2001-89990

[Patent Document 2] Publication of Unexamined Patent Application No. 2004-120274

DISCLOSURE OF THE INVENTION PROBLEM TO BE SOLVED BY THE INVENTION

Even a conveying belt that wet paper peeling performance has been improved as described above, when it is used in a press device of a paper machine in general, a wet paper contact surface tends to have dense surface and less water permeability, and become smooth through being highly pressurized for long time. Alternatively, roughness of the belt surface may be suitably modified or reconditioned according to the operational condition of the paper machine. For example, there are such cases that the paper conveying belt gets soiled, or paper quality is to be improved (in such a case that a coarser wet paper surface or higher level of paper quality is demanded). In the former case, the deteriorated belt in wet paper peeling performance due to the fact that the wet paper contact surface is smoothened after usage is dismounted once from the paper machine to recondition or change with a new belt, which causes cost increase and up-time reduction seriously.

An object of the present invention is to solve the problems described above, through providing such a paper machine and a method of paper conveying belt reconditioning by using the same paper machine that can recover the function of wet paper peeling performance deteriorated after usage and/or can suitably modify or recondition the roughness of the belt according to the operational condition of the paper machine.

MEANS FOR SOLVING THE PROBLEM

In other words, the present invention is a paper machine that has features described below in (1).

-   (1) A paper machine, comprising: a press device including a press     mechanism which pressurizes wet paper to squeeze water therefrom and     a pair of endless belt-shaped paper conveying belt for pinching and     conveying the wet paper to absorb water squeezed from the wet paper;     and a polishing device having a polisher to polish the wet paper     contacting face in order to control surface smoothness of the wet     paper contacting face of the belt on return side of at least one of     the paper conveying belts out of the paper conveying belts at such a     position so as to enable to polish the wet paper contacting face of     the belt that is running.

Further, the paper machine according to the present invention can be implemented in the following embodiments of (2) to (5).

-   (2) The paper machine according to above described (1), wherein the     polishing device further comprises a polisher arranged rotatably     which polishes the wet paper contacting face while rotating. -   (3) The paper machine according to above described (1) or (2),     wherein the paper machine includes a shifter which shifts the     polisher in a width direction of at least one paper conveying belt     out of the paper conveying belts parallel to the wet paper     contacting face to polish the wet paper contacting face by the     polisher while shifting the polisher in the width direction by the     shifter. -   (4) The paper machine according to above described (3), wherein the     polisher can be shifted by the shifter between a polishing position     of the wet paper contacting face and a retired position distanced     from the wet paper contacting face.

In addition, the present invention can achieve such an operation so as to allow recondition of the paper conveying belt while running according to a method described in (5) using the paper machine.

-   (5) Polishing a wet paper contacting face of a paper conveying belt     during a return run of the belt by means of a polishing device     disposed on a return side of the belt can control surface smoothness     of the wet paper contacting face of the paper conveying belt, the     face having been deteriorated in wet paper peeling performance due     to usage, and/or modify or recondition suitably surface roughness of     the belt according to the operative condition of the paper machine.

Furthermore, in the reconditioning method of the paper conveying belt of the above (5), the following (6) and (7) can be employed.

-   (6) The polishing operation of the above (5) is performed by     rotating polishing. -   (7) The above described rotating polishing in (6) is performed in     the width direction of the paper conveying belt.

EFFECT OF THE INVENTION

The paper machine of the present invention is provided with a polishing device on a return side of the paper conveying belt that returns from the conveyance completion point of the wet paper to the conveyance starting point of the wet paper. Polishing of the wet paper contact surface of the belt can control surface smoothness of the same, which has deteriorated in wet paper peeling performance after usage, recover the function thereof, and modify or recondition suitably the belt surface roughness according to the operational condition of the paper machine. Thereby wet paper peeling performance of the paper conveying belt can be recovered to the original condition by the machine itself, the paper conveying belt being deteriorated in wet paper peeling performance due to progressed smoothness after long period of usage, and therefore, handing over of the wet paper between each process is carried out smoothly. In addition, according to the operational condition of the paper machine, in the case that belt gets soiled or for the purpose of improving paper quality, belt surface roughness is made coarser to remove the soil of the belt and to correspond to a noble paper quality demand.

Further, the polishing device is disposed on the return side of the belt and can recover the function of the deteriorated wet paper peeling performance after usage and modify or recondition suitably the belt surface roughness according to the operational condition of the paper machine, while continuing paper manufacturing operation through polishing work of wet paper contact surface without stopping paper machine running. Consequently paper manufacturing and polishing work can be carried out simultaneously, enabling enhancement of operation efficiency.

Moreover, in a paper machine having the structure as described in (2) above, a polisher of the polishing device contacts the wet paper contacting face of the paper conveying belt while the polisher of the polishing device is rotating to polish, therefore the wet paper contacting face can be worked to have uniform surface roughness with less variation.

Also, in a paper machine having the structure as described in (3) above, the polisher can polish the wet paper contacting face of the paper conveying belt while a shifter is shifting the polisher in a width direction of the paper conveying belt and parallel to the wet paper contacting face by means of the shifter incorporated in the polishing device. Therefore the wet paper contacting face of paper conveying belt having width variation from narrow width to wide width can be polished with ease by the same polishing device.

Further, according to a paper machine having the structure as described in (4) above, the polisher can be shifted by the shifter between a polishing position of the wet paper contacting face and a retired position distanced from the wet paper contacting face. Accordingly, the polisher can stand by at the retired position when paper manufacturing is in process, and when necessary the polisher can shift from the retired position to the polishing position to polish the wet paper contacting face. In this way it is possible to eliminate the polishing device disturbance against the paper manufacturing process. Further, when polishing the wet paper contacting face, all which is required is simply to shift the polishing device from the retired position to the polishing position, which enables to polish the wet paper contacting face with ease. Thus, polishing operation of the paper conveying belt can be implemented efficiently.

Consequently, according to a reconditioning method of the paper conveying belt of the present invention using the above described paper machine, it is possible to polish the wet paper contacting face while continuing paper manufacturing operation without stopping paper machine running, to control the surface smoothness of the paper conveying belt suffering from deterioration of wet paper peeling performance after usage for reconditioning or recovering of the function whenever necessary, and further to modify or recondition suitably the belt surface roughness according to the operational condition of the paper machine. Owing to these, the paper conveying belt can be used at any time when the paper machine is running without deterioration of the wet paper peeling performance.

Furthermore, according to a reconditioning method of the paper conveying belt as described above in (6), rotating polishing is applied in the polishing step against the wet paper contacting face of the paper conveying belt, which enables to polish the wet paper contacting face into an uniform surface roughness with less variation.

According to a reconditioning method of the paper conveying belt as described above in (7), rotating polishing is applied in polishing step against the wet paper contacting face while shifting in the width direction of the paper conveying belt. Therefore the wet paper contacting face of paper conveying belt having width variation from narrow width to wide width can be polished with ease.

BEST MODE FOR CARRYING OUT THE INVENTION

Detailed description will be given hereinafter about preferable embodiments of the present invention with reference to attached drawings.

FIG. 1 is a schematic plan view of a paper machine structure according to the present invention, and FIG. 2 is an enlarged perspective view of a polishing device, which shows an essential part of the paper machine in FIG. 1.

As shown in FIG. 1 and FIG. 2, a shoe-press type paper machine as one example according to the present invention includes a press device 30 and a polishing device 40.

The press device 30 is a so-called closed draw type press device having two press mechanisms arranged in series, two press mechanisms being the first press mechanism 11 and the second press mechanism 21 disposed along a conveying direction (arrow A direction) of the wet paper W. In each press mechanism, the wet paper is conveyed in the state being pinched by a pair of belts 10 (first press mechanism), composed of paper conveying belts 10 a and 10 b and a pair of belts 20 (second press mechanism) of 20 a and 20 b respectively. Since the paper machine is a shoe-press type machine with pressurized closed draw type configuration, the wet paper can be stably conveyed with such a high speed as 1000 to 1200 m/min. Due to this arrangement, it is possible to manufacture paper with extremely high efficiency compared with a paper machine of shoe-press type with open draw type configuration.

The first press mechanism 11 includes a pair of paper conveying belts 10 having endless belt-like shape, and a first shoe 12 and a first roll 13 (a first shoe-press) arranged in opposing position with each other so that a first nip (a first pressurizing portion) is formed in the midst of the shoe and the roll. A pair of paper conveying belts 10 is laid around a plurality of rollers 31 so as to circulate passing through the gap between the first shoe 12 and the first roll 13. The first press mechanism 11 pinches and conveys the wet paper W supplied from a wire part, which is a preceding process (not shown), while squeezing water via the first shoe 12 and the first roll 13, and thereafter hands over to the second press mechanism 21 (after that the pair of paper conveying belts 10 circulate back to the original position through respective return passages).

Also, the second press mechanism 21 includes a pair of paper conveying belts 20 having endless belt-like shape, and a second shoe 22 and a second roll 23 (a second shoe-press) arranged in opposing position with each other so that a second nip (a second pressurizing portion) is formed in the midst of the shoe and the roll. A pair of paper conveying belts 20 is laid around a plurality of rollers 31 just like the pair of paper conveying belt 10 so as to circulate passing through the gap between the second shoe 22 and the second roll 23. The second press mechanism 21 receives the wet paper W supplied from the first press mechanism 11 by a pair of paper conveying belts 20 at the conveyance starting point SP, and squeezes water via the second shoe 22 and the second roll 23 while pinching and conveying the paper, and thereafter supplies the wet paper W at the conveyance ending point EP to a dryer part (not shown), which is the subsequent process (after that the pair of paper conveying belts 20 circulate back to the original position through respective return passages).

The polishing device 40 is for polishing the wet paper contacting face S of the paper conveying belts 10 and/or 20. In an example shown in FIG. 1, the polishing device is disposed at a return side of the roll side belt 20 b of the paper conveying belt used in the second press mechanism 21. The return side, herein, means the returning passage from the conveyance ending point EP of the wet paper W to the conveyance starting point SP of the wet paper W, in the case of the paper conveying belt 20.

The polishing device 40, as shown in FIG. 2, is provided with a pair of guide rails 55 disposed parallel to the width direction of the paper conveying belt 20 and a shifter 53 having sliding pieces 57 fixed on the bottom face of a base 59 and engaged sidably with the guide rails 55. A support base 61 fixed onto the base 59 supports a rotary shaft 63 rotatably, in one end of which a polisher 51 is fixed. An endless belt 71 is laid around a driven pulley 65 fixed onto the other end of the rotary shaft 63 and a drive pulley 69 of a driving motor 67. The polisher 51 is a brush-like component formed in such a way that a plenty of wire-like pieces 73, which are polishing material, are embedded in a radial pattern on a boss 75. Each wire-like piece 73 is made of brass, instead of which, for example, one made of nylon having polishing grain therein may be employed as well.

As shown in FIG. 2, the base 59 is arranged to be movable on the guide rails 55 in the direction of arrow B or C driven by a shift mechanism 77 composed of a drive motor and the like. Therefore the polisher 51 is movable between a polishing working position WP opposing the paper conveying belt 20 and a retired position RP (shown by chain lines) distanced from the paper conveying belt 20. Further, the shift mechanism 77 gives a reciprocal movement to the polisher 40 in the width direction of the paper conveying belt 20 when polishing the same.

Rotating force of the drive motor 67 is transmitted to the polisher 51 via the endless belt 71 and the polisher 51 polishes the wet paper contacting face S in the direction of the arrow D or in the reverse direction (see FIG. 1) while contacting the wet paper contacting face S of the paper conveying belt 20 with rotary motion so as to control surface smoothness of the wet paper contacting face S. That is, the polisher 51 performs rotating polishing for the whole area of the wet paper contacting face S while shifting in the width direction of the paper conveying belt 20.

It should be noted that the polishing device of the present invention is not limited to the brush type described above but other types may be employed. For example, a milling type polishing device shown in FIG. 3 may also be adopted. FIG. 3 shows a schematic side view of the milling type polishing device. As shown in FIG. 3, the polisher 51 of the milling type polishing device 50 is arranged in such a way that a plurality of blades 83 is embedded along a circumferential direction of the outside diameter of a boss 75 driven by a drive motor 67. And the milling type polishing device 50 polishes with rotary motion the wet paper contacting face S of the belt 20 while rotating blades 83. Note that for each blade 83, for example, SK1 (High Speed Steel Cutting Tool Material: HAISU) in JIS notation, SK (Carbon Steel Cutting Tool Material) in JIS notation and the like are used. Other portions are identical to what described so far. Therefore same notations or equivalent notations given to the identical portions and explanations therefor are simplified or omitted.

Further, FIG. 4 shows a schematic side view of a film polishing device, that is one of other types of polishing devices. As shown in FIG. 4, a film polishing device 60 is arranged so that a polishing film 91 supplied from a supply roll 85 runs through a backup roller 87 to be wound by a collecting roller 89, and the film 91 polishes the wet paper contacting face S of the paper conveying belt 20 contacting with pressure via the backup roller 87 against the rear face of the polishing film 91. The polishing film 91 is formed in such a way that particles of polishing material such as aluminum oxide, silicon carbide, chromium oxide, diamond and the like are adhered on the surface of belt-like base material such as polyester. As an example of this sort of film polishing device 60, model No. SP-50 made by Matsuda Incorporated and the like can be listed.

Any type of polishing device may be adopted as far as the wet paper contacting face of the paper conveying belt can be polished uniformly. For example, a polishing method enabling a sandpaper to run to polish, the sandpaper being formed with an endless belt shaped base material having diamond grains adhered on the surface thereof, which is a so-called sandpaper polishing device, a hand-holding polisher having a rotary polishing body, and the like, may be adopted.

Further, the polisher is usually used to make coarser the wet paper contacting face of the belt for the purpose of reducing sticking force with the wet paper. In case that a belt requires smoothness, the polisher can also be used to make the surface smoother. In this case, such a polishing material that can abrade the belt surface is applied, whereby smoothness of the face can be obtained. On the other hand, in some cases, the surface roughness of the belt is suitably modified or reconditioned according to the operative condition of the paper machine, in other words the belt surface roughness is altered suitably by choice, not only for obtaining smoothness but, for example, for the purpose of cleaning paper soil and improvement of paper quality (making wet paper surface coarser or corresponding to noble paper quality demands) through making the belt surface coarser.

The paper conveying belt 10; 20 can be various types and compositions and one of the examples is shown in FIG. 5. The paper conveying belt 10; 20 shown in FIG. 5 includes a base layer 25, batt layers 26(a first batt layer 26A and a second batt layer 26B) and a wet paper contacting fiber layer 27, on the surface of which a wet paper contacting face S is provided. More specifically, the first batt layer 26A is formed on a wet paper side surface of the base layer 25, the second batt layer 26B is formed on a press side surface of the base layer 25 and the wet paper contacting fiber layer 27 is formed on the wet paper side surface of the first batt layer 26A. The base layer 25, the first batt layer 26A, the second batt layer 26B and the wet paper contacting fiber layer 27 are integrated by needling.

The invention related to reconditioning method of the paper conveying belt is a method of controlling the surface smoothness of the wet paper contacting face of the belt by polishing the paper conveying belt while running, which is deteriorated in wet paper peeling performance, using the paper machine provided with a polishing device according to the present invention.

As shown in FIG. 1, the wet paper W paid out from the wire part (not shown) and handed over to the first press mechanism 11, is conveyed being pinched by a pair of paper conveying belts 10 composed of 10 a and 10 b and water is squeezed through being pressurized by the first shoe 12 and the first roll 13 and the squeezed water is absorbed by the paper conveying belt 10. Next the wet paper W is handed over to the second press mechanism 21, and conveyed being pinched by a pair of paper conveying belts 20 composed of 20 a and 20 b , and water is further squeezed through being pressurized by the second shoe 22 and the second roll 23 and the squeezed water is absorbed by the paper conveying belt 20. Subsequently the wet paper W is handed over to the dryer part (not shown) to get dried.

In the paper machine in FIG. 1, the wet paper contacting face S is polished during a return run of the belt by the polishing device 40 disposed on the return side of the paper conveying belt 20 b for the second press mechanism 21, and thereby the wet paper peeling performance is recovered. Specifically, a shift mechanism 77 shown in FIG. 2 shifts the polishing device 40 from the retired position RP distanced from the paper conveying belt 20 to the polishing working position WP where the polisher 51 opposes the paper conveying belt 20, and the drive motor 67 rotates the polisher 51 in the direction of arrow D or reverse direction to contact the wet paper contacting face of the paper conveying belt 20 for polishing the same, whereby adequate level of unevenness is formed on the wet paper contacting face and thus, the surface smoothness is controlled. In this case, the polishing device 40 polishes the wet paper contacting face S of the paper conveying belt 20 while shifting with a swing in the width direction of the paper conveying belt 20, accordingly the whole surface of the wet paper contacting face S can be polished into uniform surface roughness.

As described so far, according to the paper machine of the present invention, the wet paper contacting face S of the paper conveying belt 20 is polished to recover the deteriorated wet paper peeling performance of the paper conveying belt 20, or to modify or recondition suitably the belt surface roughness according to the operative condition of the paper machine. Therefore, usage period of the paper conveying belt 20 is significantly prolonged and the belt 20 can achieve a longer operating life. Polishing operation of the wet paper contacting face S of the paper conveying belt 20 by the polishing device 40 can be performed: during paper manufacturing operation; or after each prearranged period of time during suspending of paper manufacturing operation; or constantly. Alternatively, polishing operation by the polishing device may be started whenever faults of paper peeling happen at SP and/or EP (in many cases the paper conveying felt causes blowing phenomena, or wet paper sticks to the paper conveying felts 10, 20, resulting in paper stealing phenomena, which is a problem that the wet paper does not peel for next process).

In the above embodiment, the description was given assuming that the polishing device is disposed on the return side of the paper conveying belt in the second press mechanism. However, the polishing device can be disposed at the return side of the paper conveying belt in the first press mechanism or alternatively at both return sides in the two press mechanisms. However, especially in the down stream part of the press mechanism in a paper machine, in other words in the roll side of paper conveying belt of the second press mechanism (20 b in FIG. 1), smoothness of wet paper is required and hence the belt itself requires smoothness as well. Consequently, application effect of the present invention is enormous in that part of the press mechanism, since the invention presents significant effectiveness in improvement of wet paper peeling performance. In addition the paper machine is not limited to the shoe press type but may also be applicable to the roll press type. Further, although the description was given assuming that a press device is the one having two-step press mechanism, it is needless to say that a press device with one press mechanism or with a plurality of press mechanisms arranged in series may be adopted. Even in this case, the polishing device may be provided in a specific press mechanism or in each of the press mechanisms.

It is to be noted that the present invention is not limited to the aforementioned embodiment but modifications, improvements and the like can suitably be adopted. In addition, material, shape, dimensions, numeral figures, types, numbers, disposed places and the like of each element in the aforementioned embodiment may be discretionary, and is not restrictive as far as the present invention is attainable.

Wet paper peeling performance of the paper conveying belt can be assessed by the degree of difficulty in handing over the wet paper to the subsequent process after passing the press roll. A measuring apparatus for wet paper peeling performance is shown in FIG. 6.

In a measuring apparatus 100 shown in FIG. 6, a pair of press rolls 112, 113 and a pair of wet paper conveying belts 111 pinched by press rolls form the press part 110. The wet paper conveying belts 111 are supported by a plurality of guide rolls 115 maintaining constant tension and driven through rotation together with the press rolls 112 and 113.

In the down stream of the press part, a suction roll 121 is provided for transferring the belt to the dryer part 120; the belts are laid in endless manner and driven while being supported by guide rolls.

In addition, a doctor device 130 and a polishing device 140 are provided in the return side of the wet paper conveying belt 111 at the roll side of the press part. The doctor device 130 smoothens the surface of the wet paper conveying belt in order to reproduce the state of the belt in usage (becoming smooth due to usage) through attaching a doctor terminal 131 thereto after washing the surface of the wet paper conveying belt passing the press roll by a shower 132. The polishing device 140 polishes the smoothened surface of wet paper conveying belt by the polisher 141 to control the surface smoothness.

In the apparatus of FIG. 6, the wet paper W is mounted at the upper-stream side than the press part. The wet paper W reaches the suction roll 121 after passing the press part. The wet paper W is herein handed over to the dryer part 120 through suction by the suction roll. Wet paper peeling performance is assessed by whether the handing over is successful or failed here.

That is to say, improvement effect of the wet paper peeling performance is judged as follows. The wet paper is mounted on the wet paper conveying belt treated by the process of polishing and passes the press part, thereafter whether handing over to the suction roll is performed or not will be judged.

EXAMPLES

Running test of the wet paper conveying belt using an apparatus in FIG. 6 was carried out, and improvement effect by polishing of the wet paper peeling performance of the wet paper conveying belt was assessed. Note that the test conditions were as the followings.

1. Running Condition

(1) Running Speed of the belt: 150 m/min

(2) Pressurizing force at the press part: 40 kg/cm²

(3) Vacuum level of the suction roll: 150 mmHg

2. Wet Paper in Use

Formed by craft pulp. Basic Weight: 80 g/m², Dryness: 38%

3. Polishing Device

(1) Polishing Device: Rotary Type Sandpaper Device

(2) Polisher: #100 Sandpaper of Aluminum Oxide

4. Doctor Device

The doctor terminal is made of #600 aluminum oxide sandpaper. The doctor terminal was attached to the belt surface while the wet paper conveying belt 10 was running around, thus the state of belt in use was reproduced (smoothening through usage).

5. Structure and Properties of Press Felt

The press felt has an ordinary structure, which is formed by textile fabric and a batt layer integrated with the textile fabric by needle punch.

Basic weight: 1200 g/m²

Butt titer: 5.6 dtex

Felt density: 0.45 g/cm³

[Test 1](Standard Condition)

Using the apparatus in FIG. 6, the doctor device alone was used (the polishing device was moved to the retired position RP) to produce a wet paper conveying belt with the surface roughness of the wet paper contacting face to be Rz: 10 micrometer. Thereafter a wet paper running test was conducted to assess the belt peeling performance at the suction roll. As a result, the wet paper was not transferred to the dryer part by means of suction of the suction roll SR. This condition was reproduced as a standard condition of the belt smoothened by usage.

[Test 2]

Using the apparatus in FIG. 6, the polishing device was moved to the polishing working position WP. The wet paper contacting face was polished by several times of reciprocal travels in the width direction at a traverse speed of 100 mm/min, whereby a wet paper conveying belt with the surface roughness of Rz: 35 micrometer was produced. Then a wet paper running test was conducted to assess the belt peeling performance at the suction roll. As a result, the wet paper was transferred to the dryer part by means of suction of the suction roll SR.

[Test 3]

The wet paper contacting face of the wet paper conveying belt used in the Test 2 was abraded by the doctor terminal to obtain the surface roughness of Rz: 10 micrometer, and a running test of the wet paper was conducted similarly to the Test 1. As a result, the wet paper was not transferred to the dryer part.

[Teat 4]

The wet paper conveying belt, the surface of which was smoothened in the test 3, was re-polished to get to a roughness of Rz: 35 micrometer by the polishing device and a running test of the wet paper was conducted. As a result, the wet paper was transferred to the dryer part.

INDUSTRIAL APPLICABILITY

In a press part of a paper machine, a smooth wet paper contacting face of a paper conveying belt is required, and on the other hand excellent wet paper peeling performance is also required. It has been quite difficult to solve the both subjects simultaneously. In addition, smoothening of the paper conveying belt is further progressed due to long time running under high pressure and hence the wet paper peeling performance is deteriorated. Therefore it is extremely important for stable running of a paper machine to keep an excellent wet paper peeling performance for a long time.

The present invention is the one that solves these problems all at once. Disposing a polishing device on a return side-of the paper conveying belt can control the surface smoothness of the paper conveying belt having deteriorated in wet paper peeling performance.

According to the present invention, the paper machine can polish the wet paper contacting face while continuing paper manufacturing without stopping the paper machine running, and thereby control the surface smoothness of the paper conveying belt, the wet paper peeling performance being deteriorated, and recondition and recover the function thereof. In addition, the surface roughness of the belt can be modified or reconditioned suitably according to the operative condition of the paper machine. Owing to this, replacement of the belt and temporary stoppage of the paper machine can be eliminated and the operation efficiency can be improved through simultaneous operation of paper manufacturing and polishing.

Moreover, it is possible to polish the wet paper contacting face of the paper conveying belt by the shifter integrated in the polishing device while shifting the polisher in the width direction of the paper conveying belt and also parallel to the plane of the wet paper contacting face. Therefore the wet paper contacting face can be polished uniformly in the width direction. In addition, polishing can be performed by shifting the polisher from the retired position to the polishing position whenever necessary, which presents less opportunity to obstruct the paper manufacturing operation by polishing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 A schematic plan view of a paper machine according to the present invention.

FIG. 2 An enlarged perspective view of a polishing device in a paper machine according to the present invention.

FIG. 3 A schematic side view of a milling type polishing device.

FIG. 4 A schematic side view of a film polishing device.

FIG. 5 A longitudinal sectional view of an example of a paper conveying belt.

FIG. 6 A schematic view of a measuring apparatus for the wet paper peeling performance.

EXPLANATION OF REFERENCE NUMERALS

-   1 paper machine -   10 paper conveying belt (first press mechanism) -   10 a (shoe press side) -   10 b (roll side) -   11 first press mechanism -   12 first shoe -   13 first roll -   20 paper conveying belt (second press mechanism) -   20 a (shoe press side) -   20 b (roll side) -   21 second press mechanism -   22 second shoe -   23 second roll -   25 base layer -   26 batt layer -   27 wet paper contacting fiber layer -   30 press device -   31 roller -   40 polishing device -   40 a polishing device (polishing working position) -   40 b polishing device (retired position) -   50 milling type polishing device (polishing device) -   51 polisher -   53 shifting device -   55 guide rail -   57 sliding body -   59 base -   61 supporting table -   63 rotary shaft -   65 driven pulley -   67 drive motor -   69 drive pulley -   71 endless belt -   73 wire piece -   75 boss -   77 shift mechanism -   83 blade -   60 film polishing device -   85 supply roll -   87 backup roller -   89 collecting roll -   91 polishing film -   100 measuring apparatus for wet paper peeling performance -   110 press part -   111 wet paper conveying belt -   112 press roll -   113 press roll -   115 guide roll -   120 dryer part -   121 suction roll -   130 doctor device -   131 doctor terminal -   132 shower -   140 polishing device -   141 polisher -   S wet paper contacting face -   W wet paper -   WP polishing working position -   RP retired position -   EP wet paper conveyance completion point -   SP wet paper conveyance starting point 

1. A paper machine, comprising: a press device including a press mechanism which pressurizes wet paper to squeeze water therefrom and a pair of endless belt-shaped paper conveying belt for pinching and conveying the wet paper to absorb water squeezed from said wet paper; and a polishing device having a polisher to polish said wet paper contacting face in order to control surface smoothness of the wet paper contacting face of the belt on return side of at least one of the paper conveying belts out of said paper conveying belts at such a position so as to enable to polish the wet paper contacting face of the belt that is running.
 2. The paper machine according to claim 1, wherein said polishing device further comprises a polisher arranged rotatably which polishes said wet paper contacting face while rotating.
 3. The paper machine according to claim 1, wherein said paper machine includes a shifter which shifts said polisher in a width direction of at least one paper conveying belt out of said paper conveying belts parallel to said wet paper contacting face to polish said wet paper contacting face by said polisher while shifting said polisher in said width direction by said shifter.
 4. The paper machine according to claim 3, wherein said polisher can be shifted by said shifter between a polishing position of said wet paper contacting face and a retired position distanced from said wet paper contacting face.
 5. A reconditioning method for a paper conveying belt, comprising the steps of: polishing a wet paper contacting face of a paper conveying belt during a return run of the belt by means of a polishing device disposed on a return side of said belt; thereby, controlling surface smoothness of the wet paper contacting face of the paper conveying belt, the face having been deteriorated in wet paper peeling performance due to usage; and/or modifying or reconditioning suitably surface roughness of the belt according to the operative condition of the paper machine.
 6. The reconditioning method for a paper conveying belt according to claim 5, wherein polishing is performed by rotating polishing.
 7. The reconditioning method for a paper conveying belt according to claim 6, wherein polishing is performed by rotating polishing while shifting in the width direction of said paper conveying belt.
 8. The paper machine according to claim 2, wherein said paper machine includes a shifter which shifts said polisher in a width direction of at least one paper conveying belt out of said paper conveying belts parallel to said wet paper contacting face to polish said wet paper contacting face by said polisher while shifting said polisher in said width direction by said shifter. 